Photodetectors have been known that detect charges converted by photoelectric conversion layers. As an example of such photodetectors, a photodetector has been known that includes a photoelectric conversion layer that is disposed between a pair of electrode layers and detects, via the electrodes, charges converted by the photoelectric conversion layer.
Radiation incident on the photoelectric conversion layer scatters backward sometimes. The backscattering causes deterioration of radiation detection accuracy sometimes. For reducing the deterioration, a structure is disclosed in which an absorption scintillator made of an organic material and a backscattering scintillator made of an inorganic material having a high backscattering rate are layered. In the conventional technique, however, a read circuit for each layer of scintillator needs to be provided. It is, thus, difficult for the conventional technique to easily increase the radiation detection accuracy.